The reason that Uber would have bought its smaller rival is
so that the two companies would no longer have to compete for
customers and drivers on price. It would have been a similar
rationale to why Uber China and Didi Chuxing
merged earlier this year.

"Many of Uber’s investors wish the two had gone forward with a
deal, so that Uber would not have to keep battling for share,"
according to the Economist.

Uber may have passed on Lyft. But it has made other splashy
purchases in the meantime. Most recently, Uber bought Otto, a
self-driving truck startup, for a reported $680 million.
Kalanick told Business Insider's Biz Carson that it would
help Uber break into the "multitrillion-dollar" trucking
business.